4K HDR->SDR playback on Windows-on-ARM stutters and flickers because libplacebo regenerates its tone-map and gamut-map LUTs on every drawn frame. The two earlier workarounds targeted peak detection and HDR10+ metadata, but both regenerating LUTs log at info level, which libplacebo only does for non-dynamic LUTs, so something else is moving the LUT keys. The same libmpv build on a Snapdragon X Elite CRD (Adreno X1-85, driver 31.0.160.0) shows no churn at all, so the trigger is specific to the reporter's machine.
Add an HdrProbe to the Windows runner that polls the two LUT inputs every 250 ms - mpv's video-target-params (destination colour space, derived per frame from DXGI_OUTPUT_DESC1 and the DisplayConfig SDR white level) and video-out-params (source HDR metadata) - plus the raw DXGI output description, SDR white level and factory IsCurrent() state once a second, and reports every change and a 10 s summary into the app log as hdr-probe lines. Change streams are rate limited so an uploaded log stays within the relay's 1 MiB.
edde746
12b8c7e7ef